The present invention relates to an arrangement on a press having a eccentric shaft for adjusting the stroke of a working slide and the stroke of a counter-oscillating weight used for the balancing of masses by adjusting the resulting eccentricities of two eccentric/eccentric bush pairings of identical eccentricities arranged at the same central angle. Working connecting rods which carry the working slide are arranged on these two eccentric/eccentric bush pairings. Another eccentric/eccentric bush pairing is arranged between these two eccentric/eccentric bush pairings, the eccentrics of this third eccentric/eccentric bush pairing being offset with respect to the eccentrics of the two other eccentric/eccentric bush pairings by a central angle of 180.degree.. A mass balancing connecting rod which carries the counter-oscillating weight is arranged on the third eccentric/eccentric bush pairing. The eccentric bushes are selectively detachable and fixable in the rotating direction on the eccentrics because the bearing of the eccentric bushes on the interfering eccentrics is an interference fit with cylindrical locating surfaces established between these two parts. For the feeding of pressure oil via at least one groove, these two parts can be detached in at least one locating surface, in which case the eccentric bushes can be fixed on a part not rotating together with the eccentric shaft. In this fixed state, when the eccentric bushes are detached from the eccentrics, the eccentric shaft can be rotated for the purpose of adjusting the strokes.
In a known arrangement of this type (European Patent Document EP 0 248 917 A1), an angle generator disk is rotatably disposed directly next to each eccentric/eccentric bush pairing on a central portion of the eccentric shaft. This angle generator disk has a radial groove which is open toward the eccentric bush and in which a pin engages continuously which is in parallel to the eccentric shaft and is fastened in the adjacent eccentric bush. Each of these angle generator disks has a recess on its outer circumference into which a locking pin can be directed which is radially slidable with respect to the eccentric shaft and is otherwise arranged to be fixed to the frame. In addition, an initiator is provided on the outer circumference of each angle generator disk which can act upon an assigned sensor which is fixedly mounted on the frame. As a result, the angle position of each angle generator disk can be monitored and fixed. When the angle generator disks are locked, while the interference fits in the eccentric/eccentric bush pairings are released, their resulting eccentricities may be adjusted, specifically correspondingly for the working connecting rod as well as for the mass balancing connecting rod. It is an advantage of this known arrangement that additional bearings for the eccentric shaft may be arranged between the eccentric/eccentric bush pairings together with the angle generator disks. Also, that the resulting eccentricities for the working connecting rod, on the one hand, and the mass balancing connection rod, on the other hand, may be adjusted to be offset with respect to one another by precisely 180.degree.. A disadvantage of this known arrangement, however, is the large number of components arranged next to one another on the eccentric shaft which, when additional bearings for the eccentric shaft are included, result in an undesirably large overall width of the press.
It is therefore an object of the invention to provide a development of the arrangement of the initially described type which is suitable for a narrow construction of the press with a relatively short eccentric shaft and in which case the additional bearings for the eccentric shaft are also not necessary.
This and other objects are achieved by the present invention which provides an arrangement on a press in which the three eccentrics are arranged directly next to one another on the eccentric shaft. The two eccentric bushes carrying the two working connecting rods are provided with radially extending disks which face the transverse center plane and which each have a radial groove or a radial slot that is open toward the transverse center plane. The eccentric bush carrying the mass balancing connecting rod carries a pin which projects on both sides, is parallel to the eccentric shaft, and the projecting ends of which constantly engage in the grooves or slots in the disks of the two other eccentric bushes via sliding blocks. At least one of the two radial disks has a bore close to the outer circumference into which a locking pin can be directed which is arranged on the working connecting rod and can be slid parallel to the eccentric shaft.
The separate angle generator disks as well as the locking pins and sensors for these are therefore no longer necessary. However, the arrangement of additional bearings for the eccentric shaft between the eccentric/eccentric bush pairings together with the angle generator disks is also no longer possible. The central eccentric bush, which carries the mass balancing connecting rod, is coupled with the two outer eccentric bushes carrying the working connecting rods via the disk provided on the eccentric bushes, by means of the pins, the grooves or slots and the sliding blocks. This arrangement has the result that, for geometric reasons, the resulting eccentricities of the central eccentric/eccentric bush pairing and of the outer eccentric/eccentric bush pairings are situated offset with respect to one another precisely by a central angle of 180.degree. only in the two end positions (maximal and minimal resulting eccentricities). In the intermediate positions, there are slight deviations. However, this still results in a very good, although not complete, dynamic balancing of masses.
In certain embodiments of the invention, the eccentricities of the central eccentric/eccentric bush pairing are selected to be much larger, for example, twice as large as the eccentricities of the outer eccentric/eccentric bush pairings, whereby the counter-oscillating weight may be kept smaller.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.